This invention relates to an apparatus for effecting an additional welding to a temporarily assembled motorcar body, and, more particularly, is directed to such an additional welding apparatus at an additional welding station for effecting an additional welding between an under body and a side panel of a motorcar body, which provides the means for an additional welding of a peripheral edge of an opening portion such as a door attaching opening portion or the like thereof.
As for an apparatus of this kind, there has been hitherto known an additional welding station having an under portion welding robot for effecting an additional welding between an under body and a side member of a motorcar body disposed on the floor, and an upper portion welding robot for effecting an additional welding between a roof panel and the side member of the motorcar body suspended from a machine frame provided thereabove. This enables additional weldings of the upper portion and the under portion of the motorcar body to be effected at that single station. (See Japanese Published Unexamined Patent Application No. 108050/Showa 53 (1978)).
In this case, the portion to be welded between the roof panel and the side member is linear in form. Therefore, the upper portion welding robot, as disclosed therein, can be small in size, light in weight, and limited to only linear movement. Thus, it is possible to provide the robot suspended from a machine frame and to make a linear welding movement thereof.
However, for an additional welding of a peripheral edge of such a non-circular shaped opening portion as a door attaching opening portion or other opening portion of a motorcar body, it is necessary to use a welding gun which is moveable round in any direction of 360 degrees to face any part of the periphery edge of the opening portion. In this request, it has been general hitherto for achieving this additional welding of the same to use a large-sized general purpose robot of which a supporting arm is given a multi-directional movement function. In this case, it cannot be avoided to use the general purpose robot in such a condition that the same is placed on a floor. Consequently, it is almost impossible from a viewpoint of a floor room space to provide the same together with the under portion welding robot at a single welding station. Additionally, from such a viewpoint that the upper portion welding robot for an additional welding between the roof panel and the side member is carried out in such a manner that a welding gun thereof is inserted into the door attaching opening portion, it is also almost impossible in terms or operation to provide the same together with the general use robot at a single welding station.
Consequently, it requires additional floor space for providing a welding station used exclusively for effecting the additional welding of the peripheral edge of the opening portion. This lengthens the additional welding line. The use of the general purpose robot makes the apparatus high in price.